Compact well pumping unit actuated by linear motor with counterweight directly attached to slider

ABSTRACT

A compact well pumping unit actuated by a linear motor with one or more counterweights directly attached to the slider. In one embodiment, two slider units are joined to form a rectangular complex around a two-sided stator track mounted vertically inside of a vertical steel frame. A belt assembly connects the slider complex to the polished rod of the well pump. The belt assembly passes over a first set of pulley wheels mounted on top of the vertical steel frame and a second set mounted on the side of the vertical steel frame. Thus when the slider complex caused to moves up and down, the polished rod of the well pump is actuated by the linear motor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional application Ser. No. 60/857,622, filed Nov. 8, 2006, the contents of such application being hereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to a new apparatus for actuating a sucker rod pump on an oil well.

2. Background Art

For oil production, sucker rod pumps are typically installed in oil wells to extract the oil below which do not have enough pressure to rise to the surface. Oil is extracted by reciprocating the up and down motion of the sucker rod. Different means have been employed to actuate the sucker rod. The most popular prior art apparatus utilizes a surface mechanical pumping unit comprising of a walking beam rocking on a fulcrum as illustrated in FIG. 1. The pumping unit, placed adjacent to the wellhead 101, utilizes an electric rotary motor 102 in conjunction with a speed-reducing gearbox 103 to oscillate the walking beam 104 by means of a crank 105 and pitman 106 attached to one end of the walking beam 104. This construction converts the rapid rotational motion of the motor 102 into the relatively slow, oscillating motion of the walking beam 104. A hanger cable 107 links the free end of the walking beam 104 to a polished rod 108 emanating from the wellhead 101 at ground level. The polished rod 108 in turn is attached to the underground sucker rod (not shown). As the walking beam 104 oscillates, the sucker rod is pulled up on the power stroke, countering the weight of the sucker rod and the downward suction force in the well.

Traditional pumping units are not efficient because energy is lost when rotational force from a rotary motor is converted to a linear motion using a gearbox and oscillating walking beam. More efficient pumping units can be devised using electric linear motors that can actuate the sucker rod without the use of a gearbox and walking beam. Linear motors work much like rotary motors, except magnetic force is used to drive the moving component of the motor in a linear direction.

In a typical rotary motor as illustrated in FIG. 2, the rotor 201 (also called the armature) is compose of a series of electromagnetic coils 202 placed around the axis 203 of the rotor 201. The rotor 201 is surrounded by multiple stationary permanent magnets 204 (called stator) arranged in a circular fashion with adjacent magnets in opposite polarity. By sequentially varying the polarity of the electromagnetic coils 202 on the rotor 201, the attractive and repulsive magnetic force between the coils 202 and the magnets 204 causes the rotor 201 to spin on its axis 203.

As illustrated in FIG. 3, a linear motor works much like a rotary motor.

However, the permanent magnets 301 in the stator and the electromagnetic coils 302 in the rotor are laid out on a plane rather than in a circular fashion. In a linear motor, the moving component called the “slider” 303 moves in either linear direction on a stator formed by a track of magnets or “stator track.” To maximize the mechanical force generated, the slider (analogous to the rotor in a rotary motor) is usually composed of electromagnetic coils while the stator is composed of permanent magnets. However, the opposite configuration is also possible.

Several pumping unit designs are disclosed in U.S. Pat. No. 6,213,722 (hereinafter “'722” patent), issued Apr. 10, 2001, which uses a linear motor to actuates the sucker rod. The designs all incorporate a linear motor slider directly attached to the polished rod of the pump, but with different methods for employing a counterweight. The linear motor's stator is attached to two parallel vertical fixtures located directly above the wellhead. Although the '722 designs are more energy efficient, they have several disadvantages. These pumping units are vulnerable to vibrations produced by the linear motor. Uneven magnetic forces between the slider and the stator can cause vibrations. Since the stator is attached to a fixture on top of the well and the slider is attached to the polished rod, which is an extension of the sucker rod, vibrations from the linear motor will transfer directly onto the well structure. This could weaken seals inside the well leading to oil and/or natural gas leakage. In addition, such vibrations may gradually deform the downhole casing pipes. Since the linear motor in these designs is fixed on top of the well, maintenance and service of the wellhead and downhole components are more difficult. Furthermore, because the linear motor is fixed on the wellhead, the wellhead unit cannot withstand large pressure. Thus, extra cost for an additional design is required for the wellhead unit to withstand large pressure.

U.S. Pat. No. 7,001,157 (hereinafter “'157” patent), issued Feb. 21, 2006, addresses some of the shortcomings in the '722 patent by separating the linear motor from the pump on the wellhead. The '157 pumping unit uses a linear motor to actuate the sucker rod through a series of cables and pulleys linking the polished rod of the pump to the slider and the slider to a counterweight. As illustrated in FIG. 4, the linear motor is housed in a structure consisting of two vertical fixtures 401. The electromagnetic coils 402 for the motor are attached to both sides of the vertical fixtures 401. Unlike most conventional motors, the '157 design places the electromagnetic coils 402 on the stationary stator and the permanent magnets on the moving slider 403. There are six sets of coils 402, three along each vertical fixture 401. The slider 403 is held by two cables (404 and 405) that pass through three pulleys (406, 407, and 408) above the coil stators 402 and one pulley 409 below the coil stators 402. The first cable 404 is attached to the polished rod 410 on one end and the top side of the slider 411 on the other end. The first cable 404 hangs over two pulley wheels (406 and 407) on top of the pumping unit. A second cable 405 connects the bottom side of the slider 412 to a counterweight 413. The second cable 405 passes through a pulley wheel 409 below the coils 402, runs the length of the vertical fixture 401, and hangs over another pulley wheel 408 on top of the pumping unit.

Since the counterweight 413 hangs outside of the vertical fixture 401, it can be affected by wind and other external elements. In addition, since the horizontal clearance between the slider 403 and the coils 402 is governed primarily by the tension from the two cables, the slider 403 is prone to vibrate during operations. There is a need for a pumping unit that would address these shortcomings.

BRIEF SUMMARY OF THE INVENTION

The present invention is a compact well pumping unit actuated by a linear motor located adjacent to a sucker rod pump assembly installed in an oil well. The present invention is designed to extract liquid from a well. It combines the slider of the linear motor and the counterweight to form a single slider/counterweight motor complex. Furthermore, in the preferred embodiment, the linear motor assembly consists of two symmetrical slider/counterweight units, each with its own set of electromagnetic coils. The two slider units are joined by two connecting metal blocks to form a motor complex in the shape of a rectangular frame. The rectangular frame surrounds a two-sided stator track for the linear motor, with the two-sided stator track sandwiched between the two slider units. The two-sided stator track is comprised of a steel plate with two sets of permanent magnet bars on each side of the plate.

In the preferred embodiment, the linear motor is housed inside of a vertical support structure with a set of overturned pulley wheels mounted on top of it. The two-sided stator track is mounted vertically at the center of the vertical support structure and is supported by four standing steel I-beams. The steel plate is fixed between two steel I-beams on each peripheral end. The plate contains a plurality of permanent magnets on each side that are arranged like the steps to an upright ladder. To form the stator track, adjacent magnets on the plate are placed in opposite magnetic polarity. The four standing I-beams supporting the steel plate also serves as a railed guideway for the slider/counterweight motor complex to roll on.

In the preferred embodiment, each slider unit has two sets of roller wheels on its periphery that run on the railed guideway. Each slider unit contains a series of electromagnetic coils that are placed in the center between the two sets of roller wheels. The electromagnetic coils on the two slider units are positioned to face both sides of the stator track. When electric power is sequentially provided to the electromagnetic coils by one skilled in the art of linear motors, the slider/counterweight motor complex is urged to move up or down along the railed guideway of the stator track.

In the preferred embodiment, two belts are attached to the top side of the motor complex. These belts run to the top of the vertical support structure and hang over two overturned wheels mounted on top of the vertical support structure. The overturned wheels serve as a means to reverse the direction of the force urged on the ends of the belts. The belts then glide over a second set of overturned wheels that position the belts directly above the wellhead. The other end of the belts is attached to the polished rod emanating from the sucker rod pump mounted on the wellhead. Detachable counterweights can be place inside each slider unit to balance the weight and suction force of the sucker rod pump. As the motor complex moves up and down along the stator track, the belts, in turn, will cause the polished rod to move in the opposite direction. The well pump acquires fluid on its down stroke and transports fluid on its up stroke. Continuous up and down movements of the polished rod cause the sucker rod pump below to extract oil from an oil well. A control system is employed to control and monitor the operations of the pumping unit.

Some of the objectives of the present invention include constructing a pumping unit that is made more durable by having less moving parts and more compact by eliminating the use of a counterweight that hangs outside of the vertical support structure. In addition, the pumping unit in the present invention is less top heavy since only one pair of pulley wheels is mounted on top of the vertical support structure. By utilizing two symmetrical sliders on a two-sided stator plate, the linear motor of the preferred embodiment is designed to be more powerful and efficient. Furthermore, the clearance distance between the slider and the stator track can be adjusted to further maximize the power and efficiency of the linear motor. Lastly, the present invention is less prone to vibrations since each slider unit rolls on a precise rail attached to the stator plate.

The present invention also incorporates other useful features. The preferred embodiment incorporates an automatic cooling fan to prevent the expensive electromagnetic coils in the slider from overheating, an automatic electromagnetic emergency brake system to safeguard the linear motor in case of emergency, and soft bumpers placed above and below the stator track to soften any possible impact the sliders would have on the pumping unit structure.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a popular prior art pumping unit.

FIG. 2 illustrates a typical prior art rotary motor.

FIG. 3 illustrates a typical prior art linear motor.

FIG. 4 shows a prior art pumping unit actuated by a linear motor.

FIG. 5 shows two side views of a pumping unit in the present invention.

FIG. 6 depicts a base skid in one embodiment of the present invention.

FIG. 7 depicts a vertical steel frame in one embodiment of the present invention.

FIG. 8 depicts an upper plate in one embodiment of the present invention.

FIG. 9A shows a side view of a stator track in one embodiment of the present invention.

FIG. 9B shows the top-side view of a stator track in one embodiment of the present invention.

FIG. 10A shows the top-side of a motor complex in one embodiment of the present invention.

FIG. 10B shows a perspective view of the inside and the outside of a slider unit in one embodiment of the present invention.

FIG. 11A depicts a belt assembly for one embodiment of the present invention.

FIG. 11B shows a cross-section view of a belt used in one embodiment of the present invention.

FIG. 11C shows the ends of two belts used in one embodiment of the present invention.

FIG. 12 depicts a crown pulley system for one embodiment of the present invention.

FIG. 13 depicts two overturned wheels used in one embodiment of the present invention.

FIG. 14A depicts the structure of an electromagnetic brake used in one embodiment of the present invention.

FIG. 14B shows the movement of various parts of the electromagnetic brake when it is activated.

FIG. 15 shows a control panel mounted adjacent to the pumping unit in one embodiment of the present invention.

Like elements in the various figures are denoted by like reference numerals for consistency.

DETAILED DESCRIPTION OF THE INVENTION Overview:

In accordance with one embodiment of the present invention, the linear motor actuated pumping unit 500 is placed adjacent to the wellhead 10 as illustrated in FIG. 5. The front-side of the pumping unit 500 faces the wellhead 10. FIG. 5 presents a right-side view and a rear-side view of the pumping unit 500. The base skid 600 of the pumping unit 500 is mounted on top of a concrete foundation 20. A vertical steel structure 700 is constructed on top of the base skid 600 to support the weight of the functional components in the pumping unit 500. An upper plate 800 is attached to the top of the vertical steel structure 700. A two-sided stator track 900 is housed in the interior of the vertical steel structure 700. The bottom end of the stator track 900 is attached to the base skid 600, while the top end is attached to the upper plate 800. The slider and counterweight in the present invention are combined to form a single slider/counterweight motor complex 1000, which surrounds the stator track 900. The motor complex 1000 is attached to a belt assembly 1100, which in turn is connected it to the polished rod 30 emanating from the wellhead 10. The belt assembly 1100 hangs over a pair of overturned wheels on a crown pulley system 1200 mounted on top of the upper plate 800. The belt assembly 1100 is positioned directly over the wellhead 10 as it hangs over a second pair of overturned wheels 1300 on the front-side of the pumping unit 500. As the motor complex 1000 is driven up and down along the stator track 900, the belt assembly 1100 will transfer the motion on to the polished rod 30, thereby actuating the sucker rod of the oil pump (not shown) below the wellhead 10.

In one example embodiment, the pumping unit 500 has an eight-meter stroke and stands 12.5 meters tall. The entire pumping unit 500 can be transported pre-assembled by truck or rail.

Base Skid:

In one embodiment of the present invention, the base skid 600 is welded or bolted together using four steel I-beams (or the like) to form a rectangular base frame 601 as illustrated in FIG. 6. In one example embodiment, the base frame 601 measures 1.8 meters by 2.5 meters. The base frame 601 contains multiple mounting holes 602 which are used to bolt the base skid 600 onto a concrete foundation 20. Multiple steel structures are firmly attached to the inside of the base frame 601 to provide support.

Multiple bumpers 603 are firmly attached to the steel structure inside the base frame 601. The bumpers 603 are composed of one or more layers of soft elastic material, such as polyethylene. The bumpers 603 allow the slider/counterweight motor complex 1000 to gently come to a rest on the base skid 600, preventing the possibility of sparks on impact. The bumpers 603 are used to support the entire weight of the motor complex 1000 when the pumping unit 500 is not in operation.

A stator track connector 604, located in the center of the base frame 601, connects the base skid 600 to the lower end of the two-sided stator track 900. The stator track connector 604 firmly holds the two-sided stator track 900 in an upright position and minimizes vibrations on the stator track 900. The position of the stator track 900 can be adjusted on the stator track connector 604. Four set pins 605, located on the corners of the base frame 601, are used to attach the vertical steel structure 700 to the base skid 600. In the preferred embodiment, lift eyes 606 are placed on the base frame 601 and are used to hoist the pumping unit 500.

Vertical Steel Frame:

In one embodiment of the present invention, the vertical steel frame 700 is composed of four standing I-beams 701 supported by multiple X-beams 702 and horizontal beams 703 as illustrated in a perspective view in FIG. 7. The X-beams 702 and horizontal beams 703 are either welded or bolted onto the standing I-beams 701. In the preferred embodiment, certain X-beams 702 and horizontal beams 703 are designed to be removable so that an operator can access the interior of the pumping unit 500. In addition, the X-beam 702 on the lower front-side (facing the wellhead 10) can be removed to free up space around the wellhead 10. In the preferred embodiment, one or more interior ladders 704 can be added on the inside of the vertical steel frame 700 to allow an operator to access and service the length of the two-sided stator track 900.

Upper Plate:

In one embodiment of the present invention, the top of the vertical steel frame 700 attaches to an upper plate 800. The upper plate 800 is composed of a rectangular frame made of four steel I-beams 801 with two additional beams forming a cross inside, as illustrated in FIG. 8. The frame supports the load of the crown pulley system 1200 on top and transfers the load to the vertical steel structure 700 below. In the preferred embodiment, the upper plate 800 contains lift eyes 802 which are used to hoist either the entire pump structure or just the upper plate 800. Furthermore, a stator track connector 804 lies on the under side of the upper plate 800. The stator track connector 804 connects the upper end of the two-sided stator track 900 to the upper plate 800 and limits vibrations on the stator track 900.

Two-Sided Stator Track:

In one embodiment of the present invention, a two-sided stator track 900 is used as the stator of the linear motor. FIG. 9A illustrates a side view while FIG. 9B illustrates a top-side view of the stator track 900. The two-sided stator track 900 is analogous to a two-sided railroad track or an upright ladder with rungs made of permanent magnets. The upper end 902 of the stator track 900 attaches to the upper plate 800, while the lower end 903 attaches to the base skid 600. The stator track 900 relies on four steel I-beams 904, standing parallel upright, for strong support. In the preferred embodiment, the stator track 900 is comprised of a steel plate 908 standing vertically and bolted in between two steel I-beams 904 on the side edges. The outside surface of the steel I-beams 904 is specially designed to form the guideway on which rail wheels 1002 of the motor complex 1000 roll on. A series of evenly distributed permanent magnets 905, aligned perpendicular to and in between the four steel I-beams 904, are firmly glued to both surface-sides of the steel plate 908. The permanent magnets 905 are symmetrically placed on both surface-sides of the steel plate 908. A steel strip is bolted between adjacent magnets 905 to provide additional support. In one example embodiment, each bar of permanent magnet 905 measures 490 mm by 45 mm by 12 mm. The number and distribution of the magnets 905 on the steel plate 908 depends on the stroke length of the pump and the power output of the linear motor. Adjacent magnets 905 are placed in opposite north-south magnetic polarity with respect to the surface of the stator track 900. A thin stainless steel cover 906, fixed by bolts, covers each magnet 905 on the outside of the stator track 900. The thin stainless steel covers 906 have less magnetic conductivity than the permanent magnets 905 and are used to increase the average magnetic field and the working life of the magnets 905.

Slider/Counterweight Motor Complex:

The slider and counterweight are combined to form a slider/counterweight motor complex 1000, the primary component of the linear motor. In one embodiment, the motor complex 1000 consists of two merely identical slider units 1001 that join with two connecting metal blocks 1003 to form a rectangular frame around the two-sided stator track 900 as shown in a top-side view in FIG. 10A. In the preferred embodiment, the slider units 1001 are assembled together using bolts, but they can be joined by other means.

Each slider unit 1001 contains a series of electromagnetic coils 1010, which are covered by a silicon plate 1014 on the surface that interacts with the stator track 900. The surface is coated with a special silica gel to prevent the electromagnetic coils from being exposed to air. By sequentially reversing the polarity of electricity supplied to the electromagnetic coils 1010, one skilled in the art of linear motors can cause the motor complex 1000 to move up or down against the stationary stator track 900. The electromagnetic coils 1010 convert electric energy to mechanical force through magnetic attraction and repulsion. In the preferred embodiment, a cooling fan automatically switches on and off to cool the electromagnetic coils 1010 and keep the coil temperature at a pre-set range.

FIG. 10B shows a slider unit 1001 attached to a connecting metal block 1003 in two perspective views, showing the inside and the outside of the slider unit 1001. Each slider unit 1001 contains two sets of rail wheels 1002, one on each side of the silicon plate 1014 that covers the electromagnetic coils 1010. In the preferred embodiment, each set of rail wheels 1002 contains three steel wheels. The rail wheels 1002 are designed to roll fittingly on the rail surface of the steel I-beams 904 of the stator track 900. This rail system ensures that the motor complex 1000 travels on a straight up and down path while maintaining a precise position on the horizontal plane. This stabilizes the slider units 1001 by preventing unwanted vibration on the motor complex 1000 and stator track 900 during operations. Furthermore, the railed guideway helps to maintain a constant clearance between the electromagnetic coils 1010 of the motor complex 1000 and the permanent magnets 905 of the stator track 900, preventing the two from colliding into each other. In the preferred embodiment, this clearance distance can be adjusted to maximize the power of the linear motor. In addition, each slider unit 1001 is equipped with an oil tank which automatically lubricates the rail surface and the rail wheels 1002 at pre-set times in order to reduce friction and to further minimize vibration between the motor complex 1000 and stator track 900.

In one embodiment of the present invention, the slider unit 1001 contains multiple box-shaped openings 1011 where one or more counterweight 1013, such as lead or other metal, can be attached. The counterweights 1013 can be adjusted and balanced as needed. In addition, each slider unit 1001 has an opening on the top side for multiple electric cables 1015 to emanate from the interior. These electric cables 1015 supply electricity to motor complex 1000 and allow the control panel 1500 to monitor and control the motor complex's 1000 operation. In the preferred embodiment, an electronic coil code box 1007 is placed inside each connecting metal block 1003. The electric cables 1015 connect the coil code box 1007 to the control panel 1500, which is mounted either adjacent to the compact pumping unit 500 or in a remote location. The coil code box 1007 is an electronic component used to monitor and control the speed of the motor complex 1000, stroke length of the pump, coil temperature and amperage of the coils.

In one example embodiment, the rated output force of the linear motor is 5 tons and the maximum speed of the motor complex 1000 is 1.44 meters per second.

Belt Assembly:

In one embodiment of the present invention, a belt assembly 1100 consisting of two belts 1101, as shown in FIG. 11A, is used to connect the slider/counterweight motor complex 1000 to the polished rod 30. A different elongate flexible member, other than a belt can be used to serve the same purpose. For example, a chain, rope, cable, strap or the like can be used instead of a belt. In addition, different number of elongate flexible member can be used.

In the preferred embodiment, the belts 1101 are pressed from vulcanite (a hard rubber) with pre-strengthened steel cables 1102 inside it, as illustrated in a cross-section view in FIG. 11B. In the preferred embodiment, the ends of the belt are clamped by bridging links 1103 using a special glue, as shown in FIG. 11C. Two bridging links on each end are held together by a brace 1104. The brace 1104 in turn is attached to either the polished rod 30 on one end or the motor complex 1000 on the other end.

Crown Pulley System:

In one embodiment of the present invention, a crown pulley system 1200 is mounted directly on top of the upper plate 800. The crown pulley system 1200 includes the crown pulley mount frame 1201 (made of four steel I-beams or the like), a crossbeam 1202, two pulley wheels 1203, and multiple top bumpers 1204 as shown in FIG. 12. The pulley wheels 1203 are used to support the two belts that attach the slider/counterweight motor complex 1000 to the polished rod 30. The pulley wheels 1203 provide a means to reverse the direction of the force urged on the two ends of the belts. The crown pulley mount frame 1201 and the crossbeam 1202 support the weight placed on the pulley wheels 1203 and transfers the weight on to the vertical steel frame 700. The top bumpers 1204, made of soft elastic material, are designed to prevent the motor complex 1000 from accidentally hitting the two pulley wheels 1203. In one example embodiment, the diameter of the crown pulley wheels 1203 is 1.10 meters.

Overturned Wheels:

In one embodiment of the present invention, the belts glide a second set of overturned wheels 1300 mounted on the front-side of the vertical steel frame 700 (the side facing the wellhead 10), near the top of the vertical steel frame 700. These two overturned wheels 1300 position the belts directly above the wellhead 10, allowing the belts to align with the polished rod 30. When the pumping unit 500 is not in use, the overturned wheels 1300, shown in FIG. 13, can be turned 90 degree outwards to free up space above the wellhead 10 for service and maintenance. In one example embodiment, the diameter of the overturned wheels 1300 is 0.6 meters.

Electromagnetic Brake:

In the preferred embodiment, an electromagnetic brake system is provided to suspend the slider/counterweight motor complex 1000 in case of emergency. As displayed in FIG. 10B, each slider unit 1001 has two electromagnetic brakes 1400 located above each set of rail wheels 1002. The electromagnetic brakes 1400 prevent the motor complex 1000 from free-falling into the base skid 600 in case of emergency. For example, the electromagnetic brakes 1400 are automatically activated when there is an electrical outage or when there is a break in the connection between the motor complex 1000 and the sucker rod. Once the electromagnetic brakes 1400 are activated, the motor complex 1000 will slow down to a stop and suspend on to the standing steel I-beams 904.

The electromagnetic brake 1400 mechanism is shown detached from the slider unit 1001 in FIG. 14A. Each electromagnetic brake 1400 is comprised of the following parts: a mounting plate 1401, an electromagnetic switch 1402, a lever system 1403, two counterweights 1404, two brake pads 1405, and two wedges 1406. The mounting plate 1401 is used to attach the electromagnetic brake 1400 onto the top of the slider unit 1001, above the set of rail wheels 1002. As shown in FIG. 14B, the electromagnetic brake 1400 is activated when electricity is applied to the electromagnetic switch 1402, which causes the lever system 1403 to force the counterweights 1404 to pivot upwards. At the same time, the brake pads 1405 are pulled upwards, going deeper into the wedges 1406. This in turn causes the brake pads 1405 to squeeze in together. When the electromagnetic brake 1400 is operating on a slider unit 1001, the brake pads 1405 would squeeze the inside surface of the steel I-beam 904 (marked by “909” in FIG. 9B). When the electromagnetic brake 1400 is deactivated, the parts move in reverse to its original position. Gravity pulls the counterweights 1404 back down and the brake pads 1405 move downwards and spread apart, thereby releasing the slider unit 1001 from its grip on the steel I-beam 904.

In one example embodiment, the emergency electromagnetic brake 1400 has an effective brake distance of less than 200 mm.

Control Panel:

In one embodiment of the present invention, a control panel 1500, as illustrated in FIG. 15, is used to control and monitor the operations of the pumping unit 500. The control panel 1500 can be mounted adjacent to or away from the pumping unit 500 itself. The control panel 1500 communicates with the pumping unit 500 through wired cables, but this can also be done through wireless means. Pump operations can be monitored and controlled through a system that incorporates the control panel 1500, coil code box 1007, electronic circuitry box 1501 mounted on the vertical steel frame 700 and various sensors (not shown) placed throughout the pumping unit 500.

In the preferred embodiment, the operator can use the control panel 1500 to adjust the speed and length of stroke when the linear motor is in operation. Other settings can be adjusted when the linear motor is not in operations. The linear motor can pause for a specified “lag” time after either the up stroke or down stroke when the pump is not in operation. In addition, to maximize efficiency, the control system can automatically adjust the power of the pump in accordance to the load placed on the pump. The force and power consumption of the linear motor and the lag time can be preset prior pump operations.

In the preferred embodiment, the amperage, voltage, and resistance readings from the electromagnetic coils 1010 can be relayed first to the coil code box 1007, then to the electronic circuitry box 1501, and finally to the control panel 1500. In addition, the operator can use the control panel 1500 to monitor the coil temperature, the load placed on the slider, the amount of vibrations on the slider, and the amount of oil produced.

Furthermore, in order to protect the linear motor complex 1000, the system is designed to automatically shut off when the operating conditions go beyond certain preset ranges set at the control panel 1500. For example, the operator can set a temperature range for the electromagnetic coils 1010 to operate in. The cooling fan will automatically activate when the coils 1010 reach a certain temperature. As a last resort, the system shuts down the pump should the coils 1010 remain overheated. Similarly, the load, voltage and current on the linear motor can be monitored and controlled. The linear motor can be configured to automatically shut down should the load, voltage or current readings go beyond their preset range.

In addition, the control panel 1500 can be used to transform industrial electric current to an electric current ideal for the linear motor. For example, the control system can provide for regulated and controlled low-voltage electric power o the linear motor assembly.

The foregoing description of illustrated embodiments of the present invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed herein. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the present invention, as those skilled in the relevant art will recognize and appreciate. As indicated, these modifications may be made to the present invention in light of the foregoing description of illustrated embodiments of the present invention and are to be included within the spirit and scope of the present invention. Thus, while the present invention has been described herein with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosures, and it will be appreciated that in some instances some features of embodiments of the invention will be employed without a corresponding use of other features without departing from the scope and spirit of the invention as set forth. Therefore, many modifications may be made to adapt a particular situation or material to the essential scope and spirit of the present invention. It is intended that the invention not be limited to the particular terms used in following claims and/or to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include any and all embodiments and equivalents falling within the scope of the appended claims. 

1. A well pumping unit comprising: (a) a well pump affixed to the wellhead of an oil well; (b) a vertical support structure located adjacent to the well pump; (c) a first set of overturned pulley wheels mounted on top of the vertical support structure; (d) a second set of overturned pulley wheels mounted on the side of the vertical support structure facing the well pump and near the top of the vertical support structure; (e) a two-sided stator track having a plurality of magnets on each side, said stator track is mounted vertically inside of and parallel to the vertical support structure, said stator track having rails running vertically on both sides of the stator track; (f) a linear motor assembly having two symmetrical electromagnetic sliders joined together and affixed movably on the stator track, said linear motor assembly having one or more detachable counterweight; (g) said electromagnetic sliders having two sets of roller wheels running on rails along each side of the stator track; (h) one or more belts having one end attached to the linear motor assembly, passing through the first set and then the second set of overturned pulley wheels, and having the other end attached to the well pump; (i) a control system for providing regulated and controlled low-voltage electric power to the linear motor assembly; and whereby when power is provided to the motor assembly, the electromagnetic sliders will move in either linear vertical direction parallel to the stator plate causing the belt to move the well pump in the opposite vertical direction to extract liquid from the oil well.
 2. The well pumping unit of claim 1, wherein the electromagnetic slider can be braked by one or more electromagnetic brakes comprising of an electromagnetic switch, a pair of brake pads, and a mechanical means to squeeze the brake pads on the stator track; whereby when electricity is applied, the electromagnetic switch uses the mechanical means to causes the brake pads to squeeze the stator track, thus braking the slider on the stator track.
 3. The well pumping unit of claim 1, the electromagnetic slider is protected by bumpers placed above and below the stator track; said bumpers are made of soft elastic material.
 4. The well pumping unit of claim 1, wherein the linear motor assembly is connected by wire to a control panel; said control panel monitors and controls the linear motor assembly.
 5. The well pumping unit of claim 1, wherein the electromagnetic slider contains a fan to cool the electromagnetic slider.
 6. A device for actuating a rod of a sucker rod pump assembly, the device comprising: (a) a vertical support structure located adjacent to the sucker rod pump assembly; (b) a linear motor comprising: (i) a stator track mounted vertically on the vertical support structure, (ii) a slider able to slide on the stator track, said slider having one or more detachable counterweight, and (iii) a guideway means to stabilize the slider sliding on the stator track; (c) one or more elongate flexible member, said elongate flexible member having one end attached to the slider and the other end attached to the rod; and (d) a wheel means for reversing the direction of the force urged on the two ends of the elongate flexible member, said wheel means is mounted on the vertical support structure above the stator track; whereby when power is provided to the linear motor: (a) the slider is urged to slide up and down the stator track; (b) the end of the elongate flexible member attached to the slider moves in the same direction as the slider; (c) the direction of the force exerted on the elongate flexible member is reversed by said wheel means; and (d) the end of the elongate flexible member attached to the rod moves in the opposite direction as the slider, thereby actuating the rod.
 7. The device of claim 6, wherein the vertical support structure is a steel frame constructed from four standing steel beams connected by a plurality of horizontal and diagonal steel beams.
 8. The device of claim 7, wherein the stator track is mounted inside of the steel frame.
 9. The linear motor of claim 6, wherein the slider contains a plurality of electromagnetic coils and the stator track contains a plurality of magnets.
 10. The stator track of claim 9, wherein the plurality of magnets is covered by a thin stainless steel cover with less magnetic conductivity.
 11. The linear motor of claim 6, wherein the stator track is a two-sided stator track sandwiched between two sliders that are joined together.
 12. The linear motor of claim 6, wherein the guideway means to stabilize the slider sliding on the stator track is comprised of: (a) a plurality of wheels mounted on the slider, and (b) one or more rail mounted on the vertical support structure, said rail is mounted parallel to the stator track; whereby when the slider slides on the stator track, the wheels mounted on the slider roll on the rail, thus guiding the vertical course of the slider on the stator track while maintaining a consistent horizontal position.
 13. The device of claim 6, wherein the elongate flexible member is selected from the group consisting of a belt, chain, rope, cable, strap, or equivalent thereof.
 14. The device of claim 6, where in the elongate flexible member is a belt composed a plurality of steel cables enclosed within rubber.
 15. The device of claim 6, wherein the wheel means for reversing the direction of the force urged on the two ends of the elongate flexible member is selected from the group consisting of a pulley, overturned wheel, roller, gear or equivalent thereof.
 16. The device of claim 6, wherein the elongate flexible member passes over a wheel means for positioning the elongate flexible member directly above the rod; said wheel means is mounted on the upper end of the vertical support structure on the side of the vertical support structure facing the sucker rod pump assembly; said wheel means is selected from the group consisting of a pulley, overturned wheel, roller, gear or equivalent thereof.
 17. The device of claim 6, wherein the slider can be braked by one or more electromagnetic brake comprising of an electromagnetic switch, a pair of brake pads, and a mechanical means to squeeze the brake pads on the stator track; whereby when electricity is applied, the electromagnetic switch uses the mechanical means to causes the brake pads to squeeze the stator track, thus braking the slider on the stator track.
 18. The device of claim 6, wherein the slider is protected by bumpers placed above and below the stator track; said bumpers are made of soft elastic material.
 19. The device of claim 6, wherein the slider contains a fan to cool the slider.
 20. The device of claim 6, wherein the slider contains an oil tank to lubricate the guideway means to stabilize the slider.
 21. The device of claim 6, wherein the linear motor is connected by wire to a control panel; said control panel monitors and controls the linear motor.
 22. The linear motor of claim 21, wherein the stroke and speed of the slider can be adjusted on the control panel when the linear motor is in operation.
 23. The device of claim 21, wherein the force and power consumption of the linear motor and the lag time of the slider can be adjusted on the control panel when the linear motor is not in operation.
 24. The device of claim 21, wherein the linear motor automatically shuts off when: (a) the temperature of the slider is above a preset temperature; (b) the load on the linear motor is above or below a preset range; (c) the voltage on the linear motor is above or below a preset range; or (d) the current on the linear motor is above or below a preset range.
 25. A method for pumping a fluid utilizing a sucker rod assembly, a vertical support structure, a linear motor, a pulley wheel, one or more counterweight, one or more elongate flexible member and one or more rail; the sucker rod assembly including a rod, the linear motor including a slider and a stator track, the slider having a plurality of wheels, the elongate flexible member having two ends; the method comprising: (a) positioning the sucker rod pump assembly such that the pump contacts a fluid reservoir; (b) positioning the vertical support structure adjacent to the sucker rod pump assembly; (c) mounting the pulley wheel on top of the vertical support structure; (d) mounting the stator track on the side of the vertical support structure opposite of the sucker rod pump assembly; (e) mounting the rail to the vertical support structure such that the rail is parallel to and adjacent to the stator track; (f) attaching one end of the elongate flexible member to the rod; (g) positioning the elongate flexible member over the pulley wheel; (h) attaching the other end of the elongate flexible member to the slider; (i) positioning the slider on stator track such that the wheels of the slider roll on the rail; (j) attaching the counterweight on the slider such that it alleviates the load imposed on the linear motor by the sucker rod and the column of fluid to be pumped; and (k) operating the linear motor such that the pump acquires fluid on its down stroke and transports fluid on its up stroke. 